Problem: What is the least common multiple of 20 and 18? Another way to say this is: $\lcm(20, 18) = {?}$
Answer: The least common multiple is the smallest number that is a multiple of 20 and 18. We know that 20 x 18 (or 360) is a common multiple, but is it the least common multiple? Write out the multiples of 20 until we find a number divisible by 18. 20, 40, 60, 80, 100, 120, 140, 160, 180, So, 180 is the least common multiple of 20 and 18.